Electric adding and subtracting devices



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July 14, 1959 F. H. RAYMOD Em. 2,894,687

' ELECTRIC ADDING AND SUBTRACTING DEVICES Filed March 14, l195.? s sheefs-s'heet 1 9 D 4" HALF- ADDER DELAY Armi? wr July 14, 1959 H. RAYMOND r-:TAL 2,894,687

ELECTRIC ADDING AND SUBTRACTING DEVICES Filed March 14, 1952 8 Sheets-Sheet 2 July 14, 1959- F. H. RAYMQND ETAL ELECTRIC ADDINCAND suBTRACTING DEVICES 8 ShetsQSheet 3 Filed MarchA 14, 1952 Fisff July '14., 1959 F. H. RAYMOND ET AL 2,894,687

ELECTRIC ADDING AND SUBTRACTING DEVICES s sheets-sheet 4 Filed March 14, 1952 July 14, 1959 Filed March 14, 1952 F.H. RAYMOND ETAL ELECTRIC ADDlNG AND SUBTRACTING DEVICES 8 Sheets-Sheet 5 FiG v )maf/i" @weer oase/MS- afro/wry July 14,l 1959 F. H. RAYMOND ETAL 24,894,687

ELECTRIC ADDING AND SUBTRACTING DEVICES Filed March 14, 1952 l s sheets-sheet e (eig Tas/4 TM l " v 2455' 44o l s b l r/4Z AJuly 14, 1959v F. H. RAYMQND ETAL d 2,894,687r ELECTRIC ADDING AND suBIEAcIING DEVICES y Filed March 14, 1952 8 Sheets-Sheet 7 Fi G 8 1 fwn/ws.

Ama/ey July 14, 1959 F. H. RAYMOND ETAL 2,894,687 ELECTRIC ADDING AND suBTRAcTING DEvIEs Fild March 14, 1952 8 sheets-sheet s HMA@ 0/5 HE/VR/ @HWP/)C0 M0 'garded as forming a third United States Patent' h l 2,894,687 A y ELECTRIC ADDING AND SUBTRACTING DEVICES Franois Henri Raymond, Le Vesinet, and Roger Robert Dussine, Paris, France, assignors to Societev dElecironique et dAutomatisme, Courbevoie, France Application March 14, 1952, Serial No. 276,602 Claims priority, application France March 17, 1951 8 Claims. (Cl. 23S-176) This invention relates to electric devices for adding to, or subtracting from, each other two quantities each represented in an electrical code yby its expression in the form of the -binary-scale series:

in which, when correctly expressed, the coefficients a can of course have only one of two values, namely either or 1. The code referred to consists of an electrical pulse train which reproduces the aforementioned binaryscale series in that it consists of n equal code pulse periods (ie. time intervals during which or positions in the train where, a pulse may be present to denote a coeicient a of value l or absent to denote a coeilicient a of value 0), the code pulse periods denoting, by the sequence of their occurence, the successive terms of the binary-scale series arranged in ascending powers of the radix 2. In such an adding and subtracting device -the two quantities are fed into the device in the form of two pulse trains of this kind respectively, which will herein be called the coded input trains.

The object of the present invention is to provide an improved electric adding andsubtracting device which on receiving -two `coded input trains, without any limita- 'tion as to lengths or number of code pulse periods thereof, will produce a' similarly coded output pulse train of the same periodicity as the coded input trains so that the coded output train represents the result of either addition or subtraction, depending on a simple manual or automatic setting of the device, such result being represented by the coded output train in its correct binaryscale expression, that is to say, with all carry-over opera'- ton's effected.

In performing addition or subtraction, partial results may be formed consisting of quantities (or pulse trains representing such quantities) or digits (or pulses representing such digits), which are incorrectly expressed in the sense that they contain or are digits of value equal to or higher than the radix 2, the carry-over not having been eiected or completed; these will be herein called uncorrected and denoted, with other symbols, by the suix b, in contrast to that will be called true result or merely result quantities (trains) or digits (pulses), which have been reduced when necessary to less than radix value 'by carryover, and which will be denoted, with other symbols, by the sui'x 11.

When a numerical quantity B is added to, or subtracted from, a second numerical quantity A, the carried gures or carries taken together can obviously `be renumerical quantity R. In both addition and subtraction, this third quantity R must 2,894,687 Patented July 14, 1959 2, be considered, generally speaking, as havingto be added systematically, term by term, to the quantity B.

In electric adding and subtracting devices of the kind specified the quantity R may be represented by a third coded pulse train (herein called the carry-over train) which is progressively produced in step with the progress of the operations performed on the individual terms or digits of the quantities B and A, and with the formation term by term of the coded output pulse which represents the net result of the adding or subtracting operation. For obtaining such a net result of operation, an addition (A+B) and a subtraction (A-B) canV iu fact be Written A-l-(B-l-RL, and A-(B+R), in which (B+R) denotes that all carries have been completed when adding the quantities B and R, Whether the digits of the quantity R be produced by the addition of digits of the two quantities B and R or by the addition or subtraction of digits of the two quantities A and (Bd-Rh- The sutlix a will herein be used to denote addition, and the sutlix s to denote subtraction; the absence of any such suffix after a symbol ordinarily to be associated therewith means that the symbol is used in a context applicable to either addition or subtraction.

In operations performed term by term on quantities expressed in the binary scale, the question as to Whether a pulse (digit l) or no pulse (digit 0) should appear in any given code pulse period of the coded output train and/or of the carry-over train (for carrying into the next code pulse period) can be decided in accordance with a small number of combinations, as only three digital values are to be considered, viz. 0, l and 2. The quantity A will be expressed only with the digital values 0 and 1, and likewise the quantity (B-l-R). A simple rule of operation can be formulated for controlling or programming an addition or a subtraction of quantities represented by electric coded pulse trains. This rule of operation is quite independent of the actual conguration of the coded input 'trains B and A, and is given in the following table, in which:

The column (B4-R),7 denotes the possible digital values of the uncorrected result of addition of the quantities B and R;

The column (B-l-R)n values of the net B and R;

VThe column A denotes the of the quantity A;

The columns Sa and Ss respectively denote the possible digital values of the net results of the addition A-l-(B-l-R) A(B+R)n;

denotes the possible digital result of addition of the quantities possible digital values and of the subtraction The columns Ra and Rs respectively denote the possible digital values of the overall carry quantities produced in the addition A-i-(B-i-R) and the subtraction A-(B-l-R);

The columns R1, and R1, respectively denote the p ossible digital values lof the partial carries performed, in the addition A-l-(B-t-R) and the subtraction Af (B-,I-R) by the addition of the `quantities B and R;

The columns R2, and R2, respectively denote the possible digital values of the partial carries performed in the addition A+(B+R) and '1n the subtraction the invention is characterized in that one of said input A-(B-{-R); terminals of each half-adder 1s provided with means for Addition Subtraction (B4-Rh: (Bd-Rh A Sn Rn Ria Rin Sn Ra Rl! R2:

o 0 o o o 0 0 0 o o i i i 1 t i t i t t t 1 Dlgltsm 1 1 1 o 1 o 1 0 o o o- 2 o o 0 1 1 o 0 1 1 o 2 o 1 1 1 1 o 1 1 1 o As will be apparent, thev columns headed 8I and Ss are identical. Further, they reproduce the column headed A except in the two lines where (B-i-R)=1, the digits in the columns Sa and Ss being, for these two lines, the complements of the digital values in the column A, viz Sa=Ss=1 for A=0, and Sa=Ss=0 for A=l when (B-i-R)=l.

The columns headed REL and Rs are also identical except in the two lines where (B+R)=1. In these places, the digital values are complements of each other and they reproduce in the column Ra the digital values of 'of column A and, in the column Rs the complements of the digital values in the column A.

Further also, it is to be noted that the lack of agreement between the columns headed Ra and Rs in the lines where (B+R)=1, is due solely to the lack of agreement between the digital values of the partial carries R25 and R25. On the other hand, the partial carries in the co1- umns headed Rm and R are the same.

An electric adding device is known, which consists in essence of two components known as half-adders (see for instance Calculating instruments and Machines by D. R. Hartree, pages 100 seq. and particularly page 104). Each of the half-adders has two input terminals both connected to two circuits which may be referred to as buffer means and gating means, respectively. Buffer means may be defined, in a restricted conception, as a circuit which, having applied thereto two coded pulse trains, delivers an output pulse only when in any one period a pulse is present in one but not both of the applied pulse trains; gating means, by contrast may be defined, in a restricted conception, as a circuit which having applied thereto two coded pulse trains, delivers an output pulse only when in any one pulse period a pulse is present in both the applied pulse trains.

In the known hali-adder adding device, each halfadder has two output terminals from the so-called buier means and from the so-called gating means respectively. To the input terminals of the rst half-adder are applied the two coded input trains respectively whilst the two output terminals are respectively connected to the two input terminals of the second half-adder. At the buffer output terminal of the latter appears the coded output train representing the true result of the addition; the gating output terminal of the second half-adder is connected back to the channel connecting the gating output terminals of the second half-adder, the pulses from the gating output terminals of both half-adders having to pass through a delay element on their way to the input terminal of the second halt-adder, whereby they are delayed by a time equal to one code pulse period.

This adding device can also be used as a subtracting device by converting the coded pulse train representing the subtrahend into a coded input train representing the complement of the subtrahend for addition with one other coded input train.

An electric adding and subtracting device according to the present invention likewise comprises two half-adders, each having buffer and gating means such as defined, two input terminals to both said buer means, for delivering a result coded train, and an output terminal from said gating means, for delivering a carry coded train, and

applying thereto the two coded input trains respectively, and said result output terminal from the tirst half-adder is connected to the other of said input terminals of the second half-adder while said carry output terminals of both half-adders are jointly connected, via delaying means, to the other of said input terminals of said rst half-adder, said result output terminal of the second halfadder being adapted to deliver a coded output train from the device.

Further, said gating means of said second half-adder includes means for producing a gated pulse train appropriate to an operation of addition of the quantities represented by this coded input trains and means are also provided in said second half-adder for producing a gated pulse train appropriate to an operation of subtraction ot one of said quantities from the other, switching means being further provided which are adapted to select the one or the other of said gated pulse trains for delivery to said carry output terminal of said second half-adder.

in order to enable the invention to be readily carried into eiect, a few embodiments thereof will now be described by way of example with reference to the accompanying drawings, wherein:

Fig. 1 is a block schematic diagram showing the general arrangement of an adding and subtracting device ernbodying the invention.

Fig. 2 is an explanatory pulse train diagram graphically illustrating, by reference to a numerical example, the operation of the device of Fig. 1, both as an adder and as an adder and as a subtractor.

Figs. 3 to 9 are circuit diagrams showing respectively seven forms of electronic lay-out for a device according to the invention.

1n all gures like elements are, as far as possible, designated by the same reference numerals.

in all embodiments, 0 will denote the time interval of a pulse period of the concerned code.

The operation of the device of Fig. 1 will now be described by means of a numerical example (quantity A=53; quantity 13:27) with reference to Fig. 2. In this example it will be assumed that the transmission delays within the two half-adders l and 2 are nil. At the terminal 9, the coniiguration of the coded input train is as shown in line A of Fig. 2, and read from left to right, it is apparent that the numerical quantity A is expressed in the binary scale as 1010110. The coded input train A is applied with its code pulse periods arranged in ascending powers of 2. At the terminal 3 there is applied the coded input train B, which represents the quantity B expressed in the binary scale as 1101100, with its code pulse periods likewise appearing in the order of ascending powers of 2.

With the operator 2 set to enable the device to act as an adder, the overall delayed carry-over pulse train is as shown at RB and reads 0111111, at the input terminal 4. The mixing of both the B and Ra pulse trains at the input side of the first operator 1l represents the uncorrected result (B4-Rh, which reads 1212211. The unit value pulses are segregated for the constitution of the net partial result (B4-R07, at the terminal 5, which reads 1010011, whereas the double Value pulses which are cancelled in the output train are uniformly reduced aangaat* to 'unit value and after being'delayed by 9' appear 'at the input terminal 4 as carry Rm which reads 001011.-

The'second operator Zsimultaneously receives the coded input train vA and the coded partial result train (Bl-R)n, and the coincidence of their pulses produce a train reading l20201211. Here too, by the cancellation'of the digits 2 in the loutput 11, results in an output train S, reading 0000101 vin the binary radix numeration, i.e. reading 80, in the denary yradix numeration being the correct fsurn of 53 and 27. Simultaneously, at the other output 12 of operator 2, the carries produce a second carry train R2, which, after a delay of H, is applied to the input terminal '4 of operator 1 with other configuration 0101001.

`It 'will Ibe apparent that the overall carry train R, is

merely Vthe sum o'f 'the partial carry trains Rh, and Rza,

and it is quite easy to check that inno event can coincidence be obtained between the discrete pulses of said partial carryftrains.

It will also be seen that the various trains and series of pulses are obtained in conformity of the preceding table. Now for a subtraction process between the coded input trains A and B, the overall carry-over pulse train, RS, is configuration 0010110 and, combined with the coded input train B, the uncorrected result of addition (B4-RSL, reads 111121. The output train from the terr'niual -5 of the Iirst operator 1, (B-I-R,), reads 111101 and the partial carry train from terminal 6 and delayed by 0 -reads R1s'=000001, upon its application to the input terminal 4. In the second operator 2, now set for subtraction, the youtput'net result train SS presents the code 01011, the value of which in denary scale is 26, (S3-27), and the partial carry train R2, reads 00101 upon its application on the input terminal 4 ofthe first operator 1. Here again, the overall carry-over train Rsvresults from the mixing of the tWo partial carry trains RIS and R25, without any coincidence in time of the pulses of one with the pulses of the other of the partial carry trains.

The pulse graphs of Fig. 2 which corresponds to partial operators or half-adders 1 and 2 having no internal transmission delays, are also valid for partial operators or half-'adders l and 2 having internal transmission delays of -less than 0. This means that, in practice, 'the coded pulse trains can be set at relative phase shifts without this causing any difference, provided the phase difference remains less than the code pulse period 9.

The following embodiments will give examples of adder-subtractor devices according to the invention in some of which lthe component circuits are so chosen as to impart phase vshifts of this kindy to the coded input trains and to the series of pulses which formed during the operation process, while in others no such phase shift takes place.

In these embodiments, use will be made of an additional series of pulses, continually supplied for lthe control of the operation from a general program circuit of the computer of which the device forms part; these pulses will be called timing pulses and they occur at the frequency of the code pulse period 0. Such timing pulses will be mainly used for reshaping the incoming pulses and for deriving pulses from static storage or register means included in the partial operators.

Referring to Fig. 3, the coded input vtrain B is applied on the control grid of a tube 70 the third or suppressor grid of which receives the timing pulses T. The plate output of tube 70 is common to both tubes 70 and 74. The latter receives on its control grid the timing pulses T and on its suppressor grid the partial carry pulses R1. This plate output is also common to two other tubes 75 and 76 which respectively deliver the addition partial carry pulses R2a and the subtraction, partial carry vpulses Rzs from the second operator circuit. Onlyone of these "last tubes 75 and 76 is operative at va time, vdepending upon whether the circuit is set ffor addition or subtraction such setting being elected by the condition of a bistable trigger stage 40-`4`1, the plate outputs of which respectively control the screen grids of tubes 75 and 76. in the condition of trigger stage 40-41 indicated `Ain the drawing, where tube 41 is conductive, tube 75 is operative `and -t-he 'device acts as an adder circuit. The :appli-e cation of -a trigger pulse for instance of negative polarity tothe 'control-gridof tube 40 will reverse the conditions andthe device will then act as a subtractor. Y v

The -plate output common to all tubes 70, 74, 75 and 76 is connectedto the input tap 73 of a delay line 72, such -as an artilicial electromagnetic delay `network of well-known kind. Delay line 72 is terminated at one end on a short-circuit and at its other end on its char-v acteristic impedance so that the pulses issuing from the delay line comprise two component pulses ofo'pposite polarities. The total electrical length of delay line 72 for a pulse going first -to the short-circuited end and then returning with its polarity reversed to the output tap at the other end is-rnade equal to length of time interval of a pulse period. When negative pulses are applied at 73, :positive pulse components will appear a time 0 later on ythe input resistor 93 of the output tube 77 of the first operator circuit, in phase coincidence with 111e timing pulses T applied on suppressor grid of tube 77 with a delay 0.

From an intermediary tap of delay line 72., connection 78 applies the vsignals to the control grid of a tube 79. This tube 79 is so biassed by grid bias resistor 80 that it transmits only the pulses which are of an amplitude equal to twice the unit -amplitude,'the latter being the amplitude of any pulse issuing from any of the tubes 70, 74, 75 and 76 feeding delay line 72. The plate resistor and voltage of tube 79 are further chosen so as to limit the amplitude of the Vtransmitted pulses. Tube '79 acts as an amplitude discriminator delivering an output pulse only when it receives on its control grid a pulse resulting from thecoincidence in time of at least two component pulses.

Output lead 81 of tube 79 is connected to a -plate actuation input of a monostable trigger stage, or univibrator iii-84. This univibrator circuit is such that in its normal rest condition, tube '74 is voli` since the plate of tube 84 of the univibrator is connected through resistor 85 to the suppressor grid of tube 74. The timing pulses T on the control grid of tube 74'are not transmitted to the common plate output 4, which effectively forms the terminal vof the Afirst -operator circuit yfor the application of carry-over pulses. On the other hand, when the univibrator stage is at work, tube 84 is otr and tube 74 is on, and the `timing pulses will be delivered to delay line 7 2. This condition occurs whenever, duringany code pulse period, there appears -a pulse in the delay line 72 from theterminal 3 (train B) and simultaneously a pulse appears from the terminal 4 (train R). After being triggered to the working condition Ithe univibrator spontaneously returns to rest. The time constant of the monostable trigger stage SSL-84 is such as to enable the next timing pulse occurring `in the pulse period which immediately follows the `pulse period at which a'combined B and R .pulse enters the delay line at 73, to pass through tube 74 and to reach the input "73 of this delay line. The 'configuration shown for this univibrator stage is quite conventional; control grid of tube 83 is negatively biased at Y88, control .grid of tube 84 is positively biased at r89; both cathodes are on ground; there-is a capacitive coupling connection -frorn the plate lead 82 of tube 83 to the control grid of tube 84, and a corresponding capacitive coupling connection 90 from the plate 87 of tube 84 to the control grid of tube 83. Other circuits may be used for this purpose without departing from the scope of this disclosure.

From the output of tube 79, a lead 91 reaches an input resistor 92, so that `the plate Voltagey of tube 79 is applied to the control grid of output tube 7-7 of the iir'st 'operator and the plate voltage from 83 counteracts thenegative biasa't '94, so that any incoming pulse through Yresistor 93 is transmitted in positive polarity Ato the Y7' Control grid of tube 77. Such pulse will pass to the output of tube 77, since it is in phase with the timing pulse T on the suppressor grid. On the other hand, if tube '83 of the trigger stage is on, 1.e. if such trigger stage is at work, a double unit pulse having been applied on the control grid of the amplitude discriminating tube 79, the incoming pulse at 93 is not transmitted through the tube 77 since the control grid thereof has too much negative bias. It will be seen therefore that the amplitude discriminator 79 in conjunction with the mono-stable trigger circuit 83, 84 provides a means of registering or storing pulses of the uncorrected train (IH-Rh, and thereby controlling tube 77 and tube 74, the former acting as a means for performing the logical function of restricted union and delivering the net partial result train (B4-RL., while the latter acts as a gating means and delivers the partial carry train R1.

The corrected coded train (B4-RL, issuing from tube 77 is firstly applied through a separating resistor 95 to vthe input terminal or tap 96 of a delay line 97. Delay line 97 comprises an inductance-and-capacitance articial network and as matching resistance, and at its other end on a short-circuit. Constitution and operation of network 97 resembles those of delay line 72 of the first partial operator, but presents a first section of electrical length 0 between its input tap 98 and output tap 96 to which is applied the coded train (B-1-R). On the input tap 9S there is applied the second coded input train A the electric pulses of which have been reshaped in the input stage 99 by means of the above-mentioned timing pulses T. Reshaping stage 99 resembles shaping stage 70 for coded input train B. Delay line 97, apart from playing a part similar to that of delay line 72 in the rst operator circuit, also insures the mixing of the pulses in both coded trains A and (B-i-R). The terminal shortcircuit is preferably established on the output side of delay line 97.

The second half-adder has a portion serving for addition which is similar to the circuit of the rst, as indicated by the reference numerals which are the same in this portion of the second half-adder as those of the corresponding elements of the rst half-adder, with the addition of the marks distinguishing the corresponding elements in the second halt-adder. The coded output train S representing the final result of the operation appears at the terminal 11 from the plate of the tube 77'. The carry forming stage 75 in the second half-adder plays the very part of the carry forming stage 74 in the rst half-adder, as tube 75 is controlled by the monostable trigger circuit 83-84' in the same way as tube 74 is controlled by the monostable trigger circuit 83-8/3. When, however, the second half-adder is set to make the device act as a subtracting circuit instead of an adding circuit, the carry forming stage 75 is rendered inoperative and a subtraction carry forming stage 76 is substituted therefor. The switching into operation of the one or the other of carry forming tubes 75 and 76 is effected by means of a bistable trigger stage 14d-41, acting back on the screen grids of both tubes 75 and 76 so that one of these tubes is on when the other is ot, as already described.

The control grid of carry forming tube 76 permanently receives the coded train (B4-RL, issuing from output tube 77 of the iirst operator circuit, but delayed by 9 by means ot a delayline 100, of the same electrical constitution and characteristics as the delay line 72 in the rst operator. Its input tap receives the coded train (B4-RL, through a resistor 101, and the negative bias potential is applied at 102 for biasing the control grid of tube 76.

In a subtraction operation, the R25 train from tube 76 must have a pulse for every pulse of the net partial result train (B4-RL, except when a pulse is simultaneously present in the coded input train A. When tln's occurs, in the present embodiment, a double-unit amplitude pulse is formed at the output end of the delay line 97, and Y the amplitude discriminator 79' has triggered the univibrator 33N- 84' to its working condition before a pulse from the (B-i-R),L train has been applied to the control grid of the tube 76. Use is made of this fact to control the formation of the subtraction carry pulses R25, by controlling the suppressor grid of the tube 76 from the plate potential of the tube 83' of the univibrator. When the latter is at work, its tube 83 is on and the D.C. bias on the suppressor grid of the subtraction carry-forming tube 76 will be so low as to cut the tube 76 o and prevent any pulses applied to its control grid from reaching its plate.

In the second operator circuit of Fig. 3, a dual control of both carry forming tubes 75 and 76 is thus insured, viz. a control of the operation proper, addition or subtraction, exerted on their screen -grids from the -trigger circuit [l0-41; and a carry forming control proper from the rnonostable trigger circuit SSL-84.

An alternative of the computer circuit of Fig. 3 is given in Fig. 4. In this embodiment, both the coded trains B and R are applied in negative polarity of pulses in the control grids of the respective tubes 103 and 104. The plate outputs of these tubes are connected respectively to the ends of a resistor mixer network 10S-106 the electrical mid-point 107 of which is connected through D.C. connection 168 to the control grid of a gate tube 109. The negative bias for the control grid is applied at 116 to mid-point 107. The plate outputs of the tubes 103 and 104 are further connected respectively by D.C. connections 111 and 112 to the control and suppressor grids of a tube 113. In this way tube 113 will operate as a coincidence detector Stage, delivering the partial carry pulses R1. From the plate output 114 of tube 113, a connection 115 extends back to the suppressor grid of tube 109 so that Whenever an output R1 pulse issues from tube 113, with negative polarity, tube 109 is cut oit and delivers no output pulse. Tube 109 thus delivers coded train (B+R).

The two trains (B4-RL, and R1 issuing from the tirst operator circuits are applied respectively to input taps of two delay lines 116 and 117. These delay lines are similar in constitution and operation to those previously shown in Fig. 3, but delay line 116 has an electrical length of 0, from its input terminal to the other shortcircuited end and back to its output tap (with reversed polarity of pulses); delay line 117 has a similar electrical length of 20. The carry pulse train R1 is thus delayed by 0 with respect to the (B4-RL, pulse train. The output taps of delay lines 116 and 117 are connected to the control grids of the tubes 118 and 119 acting pulse reshaping output stages for the irst operator circuit, by virtue of the timing pulse T applied to their suppressor grids. Through a connection 126, the output of tube 119 is fed back to the input terminal 4 of the rst operator circuit.

The plate output of the reshaping tube 113 is connected to the input terminal 10 of the second operator circuit, the other input terminal 9 of which receives the coded train A which has been delayed by 0 from its instant of application at 9 in a circuit comprising a polarity inverter tube 135 followed by a delay line 136 and a reshaping stage 134i.

The second operator circuit is, for an addition, similar in principle to the first as is apparent from the choice of identical reference numerals, having merely the addition of mark for the corresponding elements of the second operator. However, the carry output tube 119 can be blocked by control trigger stage 46-41 when a subtraction operation is required, so that the carry pulses corresponding to an addition cannot reach the feedback circuit. Further, the delay line 117 of the second haliadder is made equal to 6 and not to 20 as for delay line 117 in the tirst half-adder.

The partial carry pulses for a subtraction operation are in this embodiment derived from a comparison of "'-The pulses which thus vappear-at" theplateof tube 1.22 lare of 'negative polarity andere 'due to be delayed by '50 lbefore'ftheir reinjection on the `terinir'xal'4*of the first 'operator circuit. For Athe *sake `of economy, the subtraction carry pulses 'are' applied "toV an" Vintermediary 'tap '1124' yef `-"thedelay line 117,` through -a' resistor 125. The 'tapf'124fs so arranged-as to 'pro'vide a delay of 0- for `vrthe -carry pulses -Which are 'introducedeat V"this point, and #are freected .backA from lthe short-circuited end tothe conftrol g'rid of tube'119.

Itis to be noted that, inthe device of'Fig. 4'the coded #train-S foutput appearing at the plate of tube 118 is fs'hfted by 0 with reSpectto fthe coded-input trains as ywell-as in the lcaseof the circuit of Fig. 3. Such' a phasei-shiftvcanbe avoided, if desired.

ifIn fthe valternative-embodim'ent of Fig. 5, both first and second operator-circuits lare so designed as toirequ-ire a-'-'predetermined permanent phase s'hift'bet'ween the ''tWq-inc'oming 'pulse'trairis. -In `each vperator circuit, op- =fferations lare performed by theuse of"a bistable trigger stage. -Illustrative values 'of phase shifts between vcoded "Strains, lfand between Yc'z'orresp'onding 'timing ypulses used inoperative relation 'to 'these' coded trains, for reshaping Eand y"reset, will'be mentioned, itbeing understood, how- 'fe'verg-'that ysuch lvalues may lne-varied, Aif desired.

The input terminals 3 vland 4 for the B .andiR trains vrespectively of the rst'operat'or circuit are connected vto '-the controlI grids-oftwo tubes 126 Aand"127 receiving the 'timing pulses T'on*their"suppressorfrgrids'from terminal 41431and`1i4`4 so --as to reshape the incoming pulses in fshape, 'Idurtion and 'frequency. The Iplate outputs of *bothtubes'126and127 are connected toa common actu- !fatio'n termin'al -128 of a trigger kstage Acomprising two 'tubes 1-29 `and '130 coupled in' the usual 'manner by reciprocal plate-toeg'rid `connections v"including time con- 'stantf-networks. Th'erestlconditio'n of the bistable trigger V'stage vwill be-assumed 'to'be the one in which tube 130 ison'anfd tube 1729 is olf. The control Agrid of tube A129 is "further provided with '-'a'n yasyinmetrical actuation 'input'f13`1, receiving-'the 'timing pulses` T 'shifted lby a delay 319/4, `vfor instance, for'nsur'in'g the/resetting to 'rest 'of 'this trigger fist'ag'e 'at each :code Apulse period; these 'timing pulses vshifted -by 43.9/4 'are applied Y'with nega-tive polarity to the terminal 131, whereas theotherseries Yof timing 'pulsesuserd'in 'the :embodiment of Fig. l'5 are ap- :plied with' positive polarity. The youtput vplate circuit f '-tube 129 'is -connected 'through a 'series capacitor to thec'ontrol grid 'of ia "tube '132, for the selection of lthe 'carry pulses R1 'o'f th`e nrs't operator circuit. Tube V1732 is only operative 'during the instants Vof application to its suppressor grid, 'from the terminal `146of the timing pulses lshifted in ,phase 0/4. The plate output `of tube 130 of -the trigger stage is vconnected by a `D.C. connection -to the :suppressorsgrid of Va `turbe 133 which is thus operative only when 4tubevlItO A--is oil l(work condition of the triggerstage). vTube v.133 receives on its vcontrol g'rid the permanent series -of positive timing pulses Tshifted by 0/2.

The timing pulses which will be thus transmitted .through the output tube 133 of the rst operator circuit will apparently represent the coded output train (B+R) ofthe first op" irut. These pulseswill be applied at thepoint l31-2'8' of the second operator circuit which also receives the pulses ofthe -coded inputtrain A, arrivingat 'the control g'rid of fan inverter -tube 135, delayed by -0/ 4 in a del'y line "136 nd'rshaped in a tube 1-'34 by means -of the -tir'iing pulses Tshi'ft'edjby/A applied with positive vpolarity to the suppressor-grid of tube134 from terminal v145.

Point 128' is the symmetrieal actuation input terminal of a trigger stage 12W-130', of the cnventional bifs't'able kind, included in the-second `operator circuit f Fig. f5. The circuit arrangement-of th'elatter -is apparently simi- `lar to thatof vthe rst, 'the correspndingecornponent ele-Y ments being denoted b'y the-same reference numerals as those of the irs't operation but marked Tube 130 of this trigger stageis on in the rrest condition Yofthis stage and its plate output is 'connected by -a D.`C. connection'to the `suppressor igrilof an output tube 1733 -which receives onits'feontr'ol-grid from terminal 150 the timing pulses T vshifted by 3'6/4. The other'tube 129' of the second trigger' stage has 'its plate output connected by an A.C. connection to lthe control `grid of carry forming tube 132 the suppressor grid of which receives the timing pulses shifted by 0/2 and frorn terminal 149 lwhile its screen grid is Acontrolled by the plate voltage of tube 41 of trigger stage`40'-t4l which, as in the previous embodiments is againprovided in order to'determine Whether addition or substr'acton is vto be performed. Tube 132 is so controlled by trigger stage 0f-'41 as to be operative only when Aan `additionis to be vperformed and the output lead 12 (-'l) nftube 132 Yis used for the transmission 'of the additib'ncarries Rga.

yTrigger Astage 12W-130 Vis provided with an asymmetrical resettingiactuation 'input v'at 131' which receives thev unshifted `timingpulses T, with ynegative polarity.

Subtraction carries '-Rgs "are generated, when the confr'o1 trigger stage 40e-tristan rest, by a tube 13s which has its screen grid controlled by tube 40, andthe s`u`ppressor Ygrid of which receives lthe timing pulses shifted by '0/2 Afni terminal I/ll'ivhile its control grid is connected by a capacitive connetion'to the plate output of tube 130 of trigger stage 130-1`29"t`the secondop'erator circuit. As apparent from the Atable hereinbefore Vset, in Va subtraction operation, a subtraction carry pulse will be generated whenever an 'output pulse Vappears v'in the subtraction A; (J3-ti?)7L proper.

The plate output of tub'e132 is connected to the input tap 'of a-'delay line 1li() "so'de'signed that the pulses applied thereto by tube 132 are 'transmitted after polarity reversal lto th'ec'ontrol grid of the'input carry-over tube '127 with a delay equal to '0 atl their vapplication at 141` on the input tap of delay line 140. Th'eplate outputs of 'both ltubes l132' fand 13S-are connected by the lead 142 to an intermediary input tap f thesane delay line 140. This intcrnediary'tap is spaced -b'y an electrical length of 6/4 from 4the input `ta`p connected to the output of tube 132. In the example git/'engin -Fig. 5, delay line i9 comprises three sections, 'ea'cll of P/ 4, the li'rst ttfiilliiiaieil 011 the characteristic ``6f matching 'resistance 'f the artificial line and V'the third terminated on 'a sho'rtcrcu'it -s`o that the totaldelay in this 'third section is 0/2, the polarity reversal being 'teiected vby this lshort-circuit.

To'recapitulate: thetiming pulses are vapplied in phase with coded yinput trains-A and B to lterminals 143 'and 131'; with a-phase-lagcfe/*Ll to terminals 144, 145 and 146; with -a -phase'lag efe/2 to terminals 147, 148 and 149; and vwith a phase lag -of -30/4 to terminals 131 and l150. Withlsuch values of phaseshifts, the output pulses inthe coded result train-S at 11 will'la'g by 30/ 4 behind -the-coded-input -trains'A and-B; a lag of@ could be easily obtained by applying to terminal 150 timing pulses -i`n phase with -coded input trains A and B, -but -the'resetting timing `pulses applied to terminal 131' should then -be spacedin timegslightly behind the 'pulses at 150, for instance with a delay of 0/5.

:genieen The operation of the computer arrangement of Fig. may be described as follows (omitting this time the operation of the delay lines and reshaping stages) In the general rest condition, the coded input trains A and B (assumed by way of example to be of the respective configurations shown in Fig. 2) are simultaneously applied to the input terminals 9 and 3 respectively.

The pulse existing in input train B in the first pulse period sets to work the trigger stage in the iirst operator circuit and the tube 130 of this trigger stage is turned ofi, While the tube 129 is turned on. The resulting negative output pulse from tube 129 has no action on the tube 132. The plate potential of tube 130 unblocks output tube 133. Such actuation occurs at the Zero instant of the first code pulse period. At the instant 0/4 of this trst pulse period, the pulse existing in the coded input train A reaches the actuation input of trigger stage 129'- 130 of the second operator circuit. This trigger circuit comes to work, while tube 130 is off and tube 129' on. The negative plate output from tube 129 has no action on tube 132', and the positive pulse from tube 130 has no action on tube 138. One only of tubes 132 and 138 is operative and, considering first of all an operation of addition, tube 138 is permanently rendered non-conductive s by the low bias potential of its screen grid.

Also, at the instant 0/4 of the rst code pulse period tube 132 has received a timing pulse on its suppressor grid, but as no signal then exists on its control grid, no pulse is delivered by tube 132.

At the instant 0/2 of the first code pulse period, both tubes 133 and 132 receive a timing pulse. Tube 133 delivers an output pulse which restores trigger stage 129'- 130 to rest; a positive pulse from 129' is applied to tube 132 and a carry pulse is delivered to delay line 140.

At the instant 30/4 of the rst code pulse period, tube 133 receives a timing pulse but being held non-conductive by tube 130', which is on, no output pulse is delivered to terminal 11.

Also, at the same instant 39/4, stage 129-130 in the first operator circuit is reset to rest. The pulses delivered by its tubes upon being reset, have no action on the tubes 132 and 133, respectively.

At the zero instant of the second code pulse period the rest condition of trigger stage 129130 is merely contirmed by the reset pulse, and simultaneously trigger stage 129-136 is actuated to work by the pulse existing at that instant in the coded input train B.

At the instant 0/4 of this second code pulse period, the previously formed partial carry pulse R2a is fed back from the output of the delay line 140 to the grid of tube 140 i which delivers an actuation pulse resetting to rest trigger stage 129-13t); tube 129 delivers a positive pulse to the control grid of tube 132, and a carry pulse R1.,1 is thus applied to the input tap of delay line 140 since tube 132 is at this instant rendered operative by a pulse applied via 144 to its suppressor grid. This carry pulse will be delayed by 0 so that it will not reach the grid of tube 127 until the instant 0/4 of the third code pulse period.

Also, at the instant of 0/ 4 of this second code pulse period tube 133 is rendered inoperative by 130 so that no pulse is transmitted to the second operator circuit which, at that instant does not receive a discrete pulse from the input of coded train A. No output pulse is thus delivered at 11 in the second code pulse period.

The process continues until the addition operation is completed. For instance, in the fth code pulse period wherein three pulses exist, namely one in each of the trains A, B and R (see Fig. 2), it is clear that the consecutive application of the pulses of the B and R trains to the rst operator ciruit results in a partial carry pulse being delivered to tube 132, but no pulse is transmitted to the second operator circuit which however has received a pulse of the coded input train A; tube 133 will thus deliver a result pulse at the instant 30/4 of this fifth 1.2 code pulse period, when a timing pulse is applied to its control grid at 150.

To take another example, in the last code pulse period of the operation, a single carry-over pulse exists at the instant 0/ 4 and thus an output pulse will be delivered to terminal 11 from tube 133 at the instant 30/ 4 to form a pulse in the coded output train S.

For a subtraction operation the only change is in the generation of the carry pulses in the second operator circuit. Tube 132' of the second operator circuit is unoper- -ative but tube 138 is operative. Considering again the beginning of the subtraction operation of Fig. 2, i.e. with the same coded input trains A and B, at the instant 0/ 2 of the first code pulse period trigger stage 12W-130i' is reset to rest; tube thus delivers a negative pulse and this pulse has no action on tube 138. No partial-carry pulse R25 is produced when in any one code pulse period a pulse is present in the trains B and A (but not in the train R) or in the trains R and A (but not in the train B).

ln the second code pulse period, however, the trigger ,stage 129'-130 which was at rest, since no pulse exists in coded train A, is brought to Work at the instant 0/2 by a pulse from coded input train B having been applied to trigger stage 129-136 at the instant zero of the second code pulse period. No carry-over pulse is fed back in this code pulse period. With tube 130 off, a positive pulse is delivered to carry forming tube 138. Further tube 133' thereby is rendered operative and at the instant 36/ 4 of this second pulse period the timing pulse applied at 150 is transmitted to the output terminal 11 to form a pulse in the coded output train S.

In the embodiments of Figs. 6 to 9, inclusive, which will now be described, the rst operator circuit is similar to that shown in Fig. 5. Input tubes 126 and 127 are respectively rendered operative at the zero and 0/4 instants of each code pulse period and the plate outputs of these tubes are jointly connected to the actuation point 128 of the first operator trigger stage 129-130 in which the tube 130 is conductive at rest; trigger stage 129-130 is reset by pulses applied at 131 at the instant 30/ 4 in each code pulse period; the carry forming tube 132 is made operative at the instant 0/ 4 of each code pulse period and the operativeness of output tube 133 is under the control of tube 130 of the first trigger stage. In the second operator circuit the delayed input channel for coded train A is retained but the length of delay imparted thereby to the pulses is made equal to 0/2 (instead of 0/4 as in Fig. 5) and the phase shift of the timing pulses at terminal of tube 134 is also made equal to 0/ 2. The complete feed-back channel for the carry pulses is also retained and the carry-over pulses, if any, are re-applied to terminal 4 at the instant 0/ 4 in each code pulse period. l

The partial carry pulses from the second operator circuit will also be derived at the instants 0/ 2 of each code pulse period. The operating condition of tubes 138 and 132', for subtraction and addition respectively is determined by the condition of trigger stage 411-41, as in the preceding embodiments.

Referring now to Fig. 6, the second operator circuit comprises an output tube 133' the suppressor grid of which is connected by a D.C. connection to the plate output of tube 129 of the trigger stage in the rst operator circuit so that tube 133 is only operative when, between the instants 0/4 and 319/4, the bistable trigger stage 129- 130 is at rest, viz. the quantity (B-l-R),z is zero (no pulse present). In such a case, any pulse from the coded input train A which reaches the control grid of tube 133', with positive polarity inverter stage 151 being connected to the output of re-shaping tube 134, at the instant 0/2 of a code pulse period, is passed to the output channel 11. On the other hand, if trigger stage 129;-13@ is at Work (B-l-R)=l, output tube 133' is inoperative.`

As tube 133 only delivers an output pulse when A=1 and (B+R)=O, another output stage must be provided assunse for the case'where A=0 and(Bl-.R)=^1. lThis'is obtained by mixingin the control grid lead of tu'be 133, vpositive timing pulses applied at 147 in a phase shift of 0/ 2 with the negative pulses of the coded input train A coming from tube .134 with the same /2 phase shiftand applied to the control grid of the tube 133 through a'mixing resistor 152. If a negative rA pulsecoexists with `a positive timing pulse at 147, no lpulse will be appearing at the plate of tube 133 (Ar-1, 4(Bl-R),=.1), and tube 133 will also remain inoperative if v(l'-|R)=0 regardless of whether A is then 0 or 1.

The D.C. plate potential of ltube 130 is also applied to the suppressor grids Vofthe 'two carryfformin'g 'tubes 132 and 138 of the second operator circuit, addition and subtraction carry forming tubes. 4The 'control grid of tube 132 receives the positive pulses of the A train, delayed by 0/2, from a resistance divider '1"54whic'h applies these pulses to the control grids of both thetubes 133' and 132. By this arrangement, the coexistence .in 'any code pulse period of apulse in the A train and of a pulse Yin the (B-l-R),L train (as marked by'theiconditiono'fthe trigger stage 129-130 in the first `operator circuit) initiates the formation of an addition carry pulse Rga provided tube 132 has been made operativeby bistable trigger stage 40-41.

For a subtraction operation tube 138 is made operative and the control grid of :this tube `receives through conductor 153 the mixed voltage from `resistancemixer 152, viz. the pulse voltage resulting from the mixing of the negative A trainwith the positive timing pulses, both having the above mentioned 0/2 vphase-shift. Actually, as apparent from the drawing, the control grids of both tubes 133 and 138 are connected in parallelto the output of mixer 152. Thus tube 138 vwill only form 'a subtraction carry pulse, when operative, in a code pulse period where A=O and (B-i-R)=1, and will not form 'such a pulse when A=1 and (B-l-R)=l or when'(B|-R)=O.

The rules of operation given in the table hereinbefore set out are thus also satisfied with the circuit arrangement of Fig. 6. It will be easy to check the operation of said Fig. 6 for the numerical example given in Fig. 2.

In the alternative embodiment of Fig. 7, a single tube 132 (138) is used for producing both the addition and the subtraction partial carry pulses in the second operator circuit. The control grid of this tube receives the timing pulses through an auxiliary tube 155 applied with a 0/2 phase shift at 156 of tube 155. The suppressor grid of tube 155 is controlled by the plate output of tube 130 of trigger stage 129-130in the iirst operator circuit; tube 155 only transmits the timing'pulses when (B+R)=1, as required.

The suppressor grid of the tube 132(138) receives the control voltage from the plate output of an auxiliary trigger stage 15T-158, more precisely from the plate output of tube 158 of this auxiliary trigger stage which is conductive in the rest condition thereof. Carry-forming tube 132(138) is only operative when trigger stage 157-158 is at work.

When the computer acts as an adding device trigger stage 157-158 only receives the pulse of coded input train A which is applied to its symmetrical actuation input 164), from input terminal 162 and through polarity inverter tube 161. Each time an A pulse is applied to actuation input 160, auxiliary trigger stage IS7-15S is brought to work so that tube 132(138) becomes operative at the instant 0/2 of the particular code pulse period, and a carry pulse is formed if the tube 155 is operative (A=1, (B-l-R)=1). Reset timing'pulses are permanently applied at the instance 30/4 of each code pulse period to asymmetrical reset input 159 of auxiliary trigger stage 157-158. The addition carries Rza are thus correctly derived.

When the computer acts as a subtracting device, additional actuation pulses are applied at the instants 0/4 '163 which receives on its control 'grid theftiming pulses applied at 164 applied with a -phaseshift lofvfl/ 4 and` which fis 'rendered operative by the condition of triggerstage 4d-41, controlling thebias of its suppressor grid. jTh'us, each time a pulse of :the A train has "set to work lthe rtrigger stage IS7-i158, a timing pulse from tube r163 resets the trigger stagetorest lbefore anyftirningtpuls'e applied at 156 with )a phase shift of 0/2 can reachthe control grid of tube 13211538) andno'subtraction carry pulse R25 is produced. v:For 11:1, if (-B-l-R)==-1,n"o carry pulse is formed, as required. On 4the othenhand, if the timing pulse from tube 163 reaches the ractuation input in a'code pulse period when nopulsefexists in the A train, Vthis timing pulse will Abring to'work the 'trigger stage 157-158 and tube 132(138) will become operative at the instant =0/2"of'that code pulse period. A subtraction carry pulse R25 will be 'formed in this'case 'whichcorrespondseto A=0fa`nd (B+R)=1.

The same arrangement is retained in the'alter'native embodiment of Fig. 8, vin which, however, .the 'use of-'a resistance pulse mixer yin the input of tube 133 is avoided. ln Fig. 8 the control grid of input tube 133 is connected to the plate output of tube 155 which delivers a-pulse Whenever the condition (B-l-R)=l is met in theiir'st operator circuit. The operative condition of tube 133 is simply controlled by a D.C. connection from the plate output of tube 134 to its rsuppressor grid so that any existing pulse existing inthe A train, shifted 'by 0/2 `and'delivered in negative polarity vfrom the plate .output of tube 5134, blockstube v133 so that it does not transmit any timing pulse from tube 155 in this codepulseperiod.

.On'the other handjtube 133 will be operative to transmit 'such timing pulses to output terminal 11 whenever `A':="

and y(B-|R)=l, since the timing pulse from terminal 156 is passed through 'tube 155 when (B+'R)=l, ite., when trigger stage 1129-4130 is at work.

If considered useful, instead of using Vshiftedy pulses from the A train for controlling the operative condition of output tube 133, recourse may be had to an auxiliary bistable trigger stage for such a control, such trigger stage being brought to work by existing A pulses and resetto rest by timing pulses applied with a phase shift, 'fo'r example 30/4; the plate output `of the'trigger Yfstag'efitube which is olf in its rest condition would be connected to the suppressor grid of tube 133.

Another alternative embodiment is shown in Fig. .9 wherein 'the control circuit arrangement for `both A'tubes 133 and 132(138) diiers from that shown in vFig. '8, the remaining component circuits being unchanged. The add-subtract control .trigger .stage 40-41 and the ltube 163 ofFig. y8 are retained-but not shown in Fig. 9, fand it is to be understood :that the plate output of tube 163 is connected to the input terminal 165 in lFig. i9, Athrough an inverter stage not `shown so lthat the timing pulses shifted by 0/2 (instead of .as in Fig. f8) delivered'by tube 163 kwhen operative appear with positive polarity at terminal 65.

Referring now to Fig. 9, the plate output of tube 130 of trigger stage 129-130 of the first operator circuit comprises a voltage divider 166 from which a conductoris connected to the control .grid ofa tube 167. When tube '130 is on, in the rest condition of the trigger stage,.i.e.

when (B-l-R)=0, vthe voltage applied to the control :grid oftube 167 is practically zero, whereasit is relatively high when tube 130 is off, in the work condition of this trigger stage, i.e. when (B-|R)=1.

Tube 167 is a cathodyne or cathode follower stage, having its output load in its cathode connection r168. The cathode load voltage is connected to v-a parallel resistance network 169-170-171. The other end -of resistor 169 is connected to 'the control grid of output tube v133; the other end of resistor 1'70 is connected through a unidirectionally conductive element '17,2'y to f is the control grid of tube 132 (138) as is also the other end of resistor 171 through a unidirectionally conductive element 173; such elements may advantageously be in the form of germanium crystals.

The control of the device to act either as an adding device or as a subtracting device is effected as follows: Through germanium crystals 174 and 175, the resistors 170 and 171 are respectively connected to the plates of the two triode elements of a double triode tube 176; one of these triodes is on and kthe other if oif; their cathodes are jointly connected to ground. ln the rest condition, as indicated, the lower triode is olir and the upper one is on, and the ground is thus applied to resistor 171 through crystal 175.

Thus the control grid of the tube 132(138) through the crystal 173 will be grounded when a voltage appears across the cathode load of the tube 167, being a voltage which indicates that trigger stage 129--136 has been set to work by a pulse in the (I3-HUT, pulse train. On the other hand, for these conditions, resistor 170 is ungrounded and the applied voltage is transmitted to the control grid of tube 132(13S). In this rest condition, the computer is set to act as an adding device.

When the timing pulses are applied to terminal 165, the computer will act as a subtracting device. At the instant 0/2 of each code pulse period, the positive timing pulse is applied by terminal 165 to the control grid of a triode 177, the plate and cathode of which are respectively connected to the control grids of the triode elements of tube 176. When triode 177 is conductive, the upper triode element of tube 176 is off and the lower one is on. Resistor 179 is thus grounded and resistor 171 ungrounded.

Similar switching arrangement is also provided by means of pulses existing in the corresponding input train A supplied to input terminal 178 of the control grid of a triode tube 179 controlling the condition of another double triode 180, so that, in the absence of A pulses, the upper element of double triode 180 is off and the lower element is on. The plate of the lower element is connected through a crystal 182 to the end of resistor 170, and the plate of the upper element is similarly connected to resistors 169 and 171 through the crystals 181 and 183, respectively. Terminal 178 receives the coded input train A delayed by 0/2 from the output of tube 151.

With the computer arrangement set for addition, no pulse being applied at control terminal 165, resistor 171 is grounded when no pulse exists during any code pulse period in the input train A and, if a voltage appears across the resistor at 168, indicating a condition (B-t-R)=l, then ithat voltage will be transmitted only to the control grid `of the tube 133 through resistor 169 and no carry pulse will be formed since both resistors 170 and 171 are grounded.

lf on the other hand a pulse from the coded input train A exists at the input terminal 178 and a voltage exists across the load 16S in the same code pulse period thus indicating the condition Azl, (B-|-R)=l, then resistor 169 is grounded but resistor 179 is not, and tube 132(138) will thus deliver a carry pulse in its output.

With the computer arrangement set for subtracting,

timing pulses being applied to terminal 165 during code pulse period, resistor 170 is grounded and resistor 171 is ungrounded at the instant 0/2 of each code pulse period. When Az() and (B-|-R)=l, a carry pulse is delivered by tube 132(13) and simultaneously an output pulse is delivered by tube 133 since resistor 169 is ungrounded. When A=l and (B-t-R)=l, the three resistors 169--170-171 are grounded and no pulse is delivered either into the carry channel or into the output channel. `When (B-l-R)=O, no voltage appearing at 168, whether or not an A pulse is present, no such pulse te is delivered either into the carry channel or into the output channel 11 from the tubes 132'(138) and 133, although the tube 133 will of course deliver a pulse to the output channel 11 if A=1 and (B+R)=0.

We claim:

l. In an electric computer device, comprising a rst half-adder operator and a second half-adder operator, each having rst and second actuation inputs, means in each of said operators for sequentially registering the input pulses received in said `actuation inputs and means controlled from said registering means for forming from said input pulses a pulse train representing the logical function of restricted union, and second means controlled from said registering means for forming from said input pulses a gating pulse train, means for transferring the restricted union pulse train from the first operator to a first actuation input of the second operator, means including delaying means for `transferring both gating pulse trains from the first and the second half-adder operators to a first actuation input of the first, an output channel, means for transferring the restricted union pulse train from the second operator to said output channel; and means for impressing signal pulse trains coded according to binary representation of two numerical quantities on the second actuation inputs of the first and second half-added operators, respectively.

2. An electric computer device according to claim 1, wherein said registering means comprise amplitude-discriminator means actuating a trigger circuit.

3. An electric computer device according to claim l. wherein said registering means comprises impulse binary counting means.

4. An electric computer device comprising a rst halfadder operator and a second half-adder operator, each having rst and second actuation inputs and a plurality of outputs, said second half adder having an additional input, means in said rst half-adder operator coupled to its actuation inputs and performing on its input pulse trains the logical function of restricted union for forming at two separate outputs restricted union pulse trains respectively representative of the net result of addition of said input trains and of the complement of said result of addition, gating means in said lirst half-adder operator for also deriving from its actuation inputs a gating pulse train representative of the carry-over quantity resulting fom said addition operation, transfer means from the restricted union output of said rst operator representing said net result of addition to a first actuation input of said second half-adder operator, means in said second half-adder operator coupled to its actuation inputs and performing on its input pulse trains the function of restricted union for forming at two separate outputs restricted union pulse trains, one of the input pulse trains being the restricted union pulse train from the rst half-adder operator representing the complementary result of addition; transfer means to introduce the complementary result of addition to the additional input of said second half adder operator, and gating means in said second half-adder operator for deriving from its actuation inputs a gating pulse train `representative of the carry-over quantity resulting from the addition operation of its two input trains, gating means in said second half-adder operator for also deriving from its actua- Lion inputs a gating pulse train representative of a subtraction operation between its input pulse trains, switching means for directing the one or the other of said gating pulse trains to a carry-over output of said second half-adder operator, delaying means having several inputs and an output, the latter being connected to a first actuation input of the iirst half-adder operator, transfer means for applying both Ithe gating pulse train from the First operator and the selected gating pulse train in said second operator to respective inputs of said delaying means, and transfer means for applying on the second actuation inputs of said first and second half-adder operators respectively signal pulse trains coded according to the binary representation of two numerical quantities.

5. An electric computer device according to claim 4 comprising means in said first operator for producing a gating pulse train representative of the complement of the addition carry-over pulse train wherein said gating means for deriving a subtraction carry-over pulse train are operatively controlled both by the gating pulse train from fthe rst operator representative of said complement of the addition carrydover train and by the numerical quantity representative signal train applied on said second half-adder operator.

6. An electric computer device according to claim 4, wherein said gating means for deriving a subtraction carry-over pulse train are operatively controlled by both the additional result pulse train from the rst half-adder operator and the addition carry-over gating pulse train in said second half-adder operator.

7. An electric computer device according to claim 4, comprising means in said second operator for producing a pulse train complementary to the signal pulse train representing the numerical quantity and wherein said gating means for deriving a subtraction carry-over pulse train are operatively contolled by both the addition result pulse train from the rst half-adder operator and said complementary train of the signal pulse train representing the numerical quantity in said second half-adder operator.

8. In an electric computer device, first half-adder operator and a second half-adder operator, each operator including first and second actuation inputs and output terminals, including a lrst actuation input for receiving a coded signal train of binary number representative pulses; said first half-adder operator including gating means coupled to its actuation inputs `and means coupled to its actuation inputs and for performing on the input pulse trains the logical function of restricted union for simultaneously deriving from said input pulse trains an addition carryover pulse train and a corrected addition result pulse train, respectively, said restricted union means in said rst operator being connected at least to a rst output terminal of said first operator; said second halfadder operator including input gating means `and means for performing on the incoming pulse trains the logical function of restricted union for selectively deriving from said input pulse trains addition or subtraction carryover pulse trains as well as a corrected result pulse train, respectively; an output terminal from said restricted union means in said second operator being coupled to a second actuation input in said first operator, second output terminal in said second operator, and a control switch in said second operator for passing only one or or the other of said carryover pulse trains to said second output terminal, delaying means connecting a second actuation input of said second operator to both the second output terminals of said first and second operators.

References Cited in the le of this patent UNITED STATES PATENTS 2,590,950 Eckert Apr. 1, 1952 2,596,199 Bennett May 13, 1952 2,600,744 Eckert June 17, 1952 2,643,820 Williams June 30, 1953 2,646,501 Eckert July 21, 1953 2,803,401 Nelson Aug. 20, 1957 2,808,983 Uttley Oct. 8, 1957 FOREIGN PATENTS 1,008,424 France Feb. 20, 1952 1,029,204 France Mar. 4, 1953 707,784 Great Britain Apr. 1, 1954 OTHER REFERENCES Calculating Instruments and Machines by Hartree, Univ. of Ill. Press, 1949; pages 103-106, total of three sheets.

Proceedings of lthe IRE, Standards on Electronic Computers; Definitions of Terms, 1950; pages 271-277. Page 272 relied on. March 1951.

Proceedings of the Institute of Electrical Engineers. Part II April 1952. Pages 107-123. 

